Device for variable actuation of the gas exchange valves in internal combustion piston engines

ABSTRACT

The invention relates to a revolving gear consisting of a housing (G), a shaft (W), an intermediate member (Z) and an output member (A). The shaft is revolvably guided in the housing in a rotating joint (wb) and actuates the intermediate member by means of a curved joint (zw). The intermediate member is supported by a curved joint (zg) in the housing and is actively connected to the output member by another curved joint (za). The curved joint between the intermediate member and the housing has a controlling section enabling movement to be transmitted to the output member and a locking section preventing movement from being transmitted to the output member. The output member is unequivocally guided in the housing and transmits movement to at least one valve (V).

It is known that the travel path of the gas exchange valves in internalcombustion engines has a decisive influence on the operating performanceand the performance data of the motor. In particular for the reductionof gas-exchange losses in charge-mass-controlled motors, a valve travelpath that can be constantly changed in the operation of the motor ispreferable. Thereby, a change in the travel path from intake and exhaustvalves as well as a change only in the intake valves can beadvantageous. Four-element gear boxes (e.g. DE 38 33 540 C2, DE 43 22449 A1, BMW Valvetronic) is known for the technical implementation ofsuch variable valve control. Such valve gear boxes enable anuninterrupted change in the valve travel path during the operation of amotor.

The goal of the invention given in patent claim 1 is to fulfill therequirements set by the motor for a variable valve control better thanthe state of the art. These requirements are characterized for one inthe design of the individual valve travel paths and secondly in the sizeof the mechanical loss through friction during the actuation of thevalves. The individual valve travel paths and the producible host ofvalve travel paths must be as freely constructed as possible withrespect to the aperture angle, closure angle, valve stroke, valveacceleration course, and phasing to the crank angle. Losses due tomechanical friction should be kept to a minimum. These requirementsshould be fulfilled to the greatest extent possible without additionalconstructional effort, in particular an increase in overall height.

This goal is fulfilled through the characteristics, listed in patentclaim 1, of a gear box for the actuation of the valves.

The gear box consists of an actuating shaft (W), which is revolvablyguided in the housing (G) in a swivel joint (wg) and which actuates anintermediate member (Z) via a curved joint (zw). This intermediatemember (Z) is supported for one by a curved joint (zg) in the housing(G), for example in the cylinder head and is connected with an outputmember (A). The curved joint (zg) between the intermediate member (Z)and the housing (G) consists of a section forming a bosh and acontrolling section. For changing the valve stroke, it is provided todesign in a changeable manner the position (a) of the controllingsection to the curved joint (zg) of the shaft (W) in the housing (G) inthe motor operation. The output member (A) is clearly guided in thehousing (G), for example in a curved joint (ag), and transmits themovement to at least one valve (V).

The advantages gained with the invention result from the fact that theintermediate member (Z) is connected with the output member (A) via acurved joint (za), thereby reducing the number of joint valences on theintermediate member actuated by the shaft (W) and simultaneously thetotal number of joint valences of the gear box. Contrary to the knownstate of the art, the gear box has an additional degree of freedom ofmovement, which allows a displacement of the intermediate member (Z)relative to the output member (A) along the cam of the curved joint (za)between the intermediate member (Z) and the output member (A) and asimultaneous rotation of the intermediate member (Z) relative to theoutput member (A) around the curved joint (za) between the intermediatemember (Z) and the output member (A). With the curved joint (za) inaccordance with the invention that is between the intermediate member(Z) and the output member (A), the movement of the intermediate member(Z) and thus the movement transmission from the actuating shaft (W) tothe output member (A) and thus to the valve (V) can be designed withmore freedom that with the state of the art.

The additional degree of movement freedom causes a roll motion of theintermediate member (Z) on the output member (A). This rotary motioncauses a displacement flow of the lubricant, which supportssignificantly the formation of a sustainable lubricating film in thecontact of intermediate member (Z) and output member (A). The rotarymotion also partially reduces the sliding speed in the contact pointthrough a roll motion. Each of these effects reduces the friction in thenamed contact point.

The design in accordance with the invention also has the advantage thatit does not require more space compared to the state of the art.

Patent claim 2 describes the advantageous design of the contour (Kza orKaz) of one of the two contact partners in the curved joint (za) betweenthe intermediate member (Z) and the output member (A) as a levelsurface.

The production of the components is therefore less expensive and moreexact than with the freely designed contour of both gear members.

Patent claim 3 describes the advantageous design of the contour (Kazor/and Kza) of at least one of the two contact partners in the curvedjoint (za) between the intermediate member (Z) and the output member (A)as a circular arc. The production of the component is therefore lessexpensive and more exact than with the freely designed contour of thegear members.

Patent claims 4-7 describe additional advantageous designs of the curvedjoints.

By designing the curved joint such that the curved-joint-determiningcontour is only attached to the one contact partner, the contour of theother contact partner will be a circular arc or a circle, which ispreferably designed as a revolvable cable roll. Thereby, in this curvedjoint, a rolling off of the contact partner on thecurved-joint-determined form is achieved and the tangential movement isshifted to the bearing of the revolvable cable roll. The friction inthis curved joint is reduced through the materials known for slidebearings and lubrication ratios and through the use of a small frictionradius.

Patent claim 4 describes an embodiment of the gear box in which thecurved-joint-determining contour of the curved joint (zg) between theintermediate member (Z) and the housing (G) is formed exclusively by thecontour (Kzg1) on the intermediate member (Z) and in which the contour(Kgz1) of the housing-side support is a revolvable cable roll (FIG. 2).

Patent claim 5 describes an embodiment of the gear box, in which thecurved-joint-determining contour of the curved joint (zg) between theintermediate member (Z) and the housing (G) is formed exclusively by thecontour (Kgz2) on the housing (G) and the curved-joint-determiningcontour (Kzg2) is a revolvable cable roll (FIG. 3).

Patent claim 6 describes an embodiment of the gear box, in which thecurved-joint-determining contour of the curved joint (zw) between theintermediate member (Z) and the shaft (W) is formed exclusively by thecontour (Kwz1) on the shaft (W) and the curved-joint-determining contour(Kzw1) is a revolvable cable roll (FIG. 4).

Patent claim 7 describes an embodiment of the gear box, in which thecurved-joint-determining contour of the curved joint (za) between theintermediate member (Z) and the output member (A) is formed exclusivelyby the contour (Kaz1) on the output member (A) and thecurved-joint-determining contour (Kza1) is a circular arc (FIG. 5) or arevolvable cable roll.

Patent claim 8 describes embodiments in which the friction of the gearbox is further reduced through the use of various friction-reducingeffects in the curved joint on the intermediate member (Z).

Patent claim 9 describes embodiments of the curved joints, in which thefriction in the curved joints on the intermediate member (Z) is furtherreduced through the use of an anti-friction bearing for supporting arevolvable cable roll.

Patent claim 10 describes the advantageous design of the intermediatemember (Z), in which at least two of the curved joints on theintermediate member (Z) are represented on the intermediate member sidethrough rotating bodies and at least two of the rotating centers ofthese rotating bodies overlap. In this manner, the designed space isminimized and the power resulting from the angular acceleration of theintermediate member (Z) is reduced.

In an extreme case, all three curved joints on the intermediate member(Z) are represented on the intermediate side through rotating bodies andall three rotating centers overlap (FIG. 6). In this manner, thesmallest designed space requirement is attained. The pivot position ofthe intermediate member (Z) as a degree of freedom of movement freedomis then meaningless for the transmission of movement.

Patent claim 11 shows that the number of joints and the moved masses canbe reduced through a joint actuation of several output members (Ai) andvalves (Vi) of a cylinder via a cam (N) and an intermediate member (Z),which advantageously reduces the friction and minimizes theconstructional effort through the reduction of the number of components(FIG. 7).

Patent claims 12 and 13 shows that the curve (Kgz2) forming the curvedjoint (zg) between the intermediate member (Z) and the housing (G) inthe housing (G) consists of a part (g1) forming

the valve bosh and a part (g2) forming the controlling section. As anexample, the part (g2) forming the controlling section can be affixed ina revolvable manner in a push part (S) and the push part (S) can beaffixed in the housing (G) in a relocatable manner. The displacementposition (rs) of the push part (S) can, for example, be set through acam (VNs) clamped in the housing (G). The rotary motion (rd) of the part(g2) forming the controlling section can be set through a cam (VNd)clamped in the housing (G) or through a cam (VNd) clamped in the pushpart (S). In this manner, the rotary motion (rd) of the part (g2)forming the controlling section can be set independently of thedisplacement position (rs) of the push part (S). In the simplest case,the rotary motion (rd) is controlled by a cam located in the housing (G)through the displacement (rs) of the push part (S).

In this way, the position (a) of the radial cam in the direction of thebosh can be implemented in a displaceable (rv) and rotatable (rd) mannerin order to modify the valve cam. This further increases the designfreedom of the valve cam. A contact loss of the gear members does notoccur. In particular, the valve acceleration and the valve stroke canalso be modified with the same valve opening angle (FIG. 8).

The part (g1) forming the bosh section in the housing (G) can be used toguarantee the reset movement of the intermediate member (Z) and thus thecam contact, in that it is seated in a pivotable manner in the housing(G) and exerts a force on the intermediate member (Z), which moves thistowards the cam (N).

This force is created for example via a spring force (KF). With thistype of design, the necessary spring travel can be very small (FIG. 9).

1. Device for the variable actuation of the gas exchange valves ininternal combustion piston engines, consisting of a housing (G), a shaft(W) seated in the housing (G) in a pivotable manner, the movement ofwhich comes from the crank shaft, a output member (A), which is clearlyguided in the housing (G) and transmits the movement to the gas exchangevalve (V) and an intermediate member (Z), which is connected with theshaft (W) and with the housing (G) via exactly one curved joint (zw, zg)and with the output member (A) via an additional joint (za), whereby thecam in the curved joint (zg) between the intermediate member (Z) andhousing (G) has a section forming a bosh and a controlling section, theposition of which can be set to the shaft (W) for the modification ofthe valve cam, characterized in that the joint (za) between theintermediate member (Z) and the output member (A) is a curved joint. 2.Device in accordance with claim 1, characterized in that one of thecontours (Kaz, Kza) forming the curved joint (za) between theintermediate member (Z) and the output member (A) is formed on theintermediate member (Z) and on the output member (A) via an evencontour.
 3. Device in accordance with claim 1, characterized in that atleast one of the contours (Kaz, Kza) forming the curved joint (za)between the intermediate member (Z) and the output member (A) is formedon the intermediate member (Z) and the output member (A) via a segmentof a revolvable rotating body.
 4. Device in accordance with claim 1,characterized in that the curved joint (zg) between intermediate member(Z) and housing (G) is formed via a revolvable rotating body mounted inthe housing (G) and via a cam (Kzg1) on the intermediate member (Z). 5.Device in accordance with claim 1, characterized in that the curvedjoint (zg) between intermediate member (Z) and housing (G) is formed viaa revolvable rotating body attached on the intermediate member (Z) andvia a cam (Kgz2) in the housing (G).
 6. Device in accordance with claim1, characterized in that the curved joint (zw) between intermediatemember (Z) and shaft (W) is formed via a revolvable rotating bodyattached on the intermediate member (Z) and via a cam (Kwz1) on theshaft (W).
 7. Device in accordance with claim 1, characterized in thatthe curved joint (zw) between intermediate member (Z) and output member(A) is formed via a revolvable rotating body attached on theintermediate member (Z) and via a cam (Kaz1) on the output member (A).8. Device in accordance with claim 4, characterized in that at least twoof the curved joints on the intermediate member (Z) are formed viarevolvable rotating bodies.
 9. Device in accordance with claim 4,characterized in that at least one of the revolvable rotating bodiesattached on the intermediate member (Z) is formed via a part of theanti-friction bearing.
 10. Device in accordance with claim 8,characterized in that at least two of the rotating centers of therevolvable rotating bodies attached at the intermediate member (Z)overlap.
 11. Device in accordance with claim 1, characterized in thattwo or more valves (Vi) of a cylinder are actuated from an intermediatemember (Z) via one or more output members (Ai).
 12. Device in accordancewith claim 8, characterized in that the cam forming the curved joint(zg) between intermediate member (Z) and housing (G) is represented viaa contour forming the bosh area in the housing or on a part (g1) mountedin the housing and via a contour forming the controlling section onanother part (g2).
 13. Device in accordance with claim 6, characterizedin that the radial cam forming the curved joint (zg) betweenintermediate member (Z) and housing (G) is modifiable with respect todisplacement and rotation.
 14. Device in accordance with claim 2,characterized in that the curved joint (zg) between intermediate member(Z) and housing (G) is formed via a revolvable rotating body mounted inthe housing (G) and via a cam (Kzg1) on the intermediate member (Z). 15.Device in accordance with claim 3, characterized in that the curvedjoint (zg) between intermediate member (Z) and housing (G) is formed viaa revolvable rotating body mounted in the housing (G) and via a cam(Kzg1) on the intermediate member (Z).
 16. Device in accordance withclaim 2, characterized in that the curved joint (zg) betweenintermediate member (Z) and housing (G) is formed via a revolvablerotating body attached on the intermediate member (Z) and via a cam(Kgz2) in the housing (G).
 17. Device in accordance with claim 3,characterized in that the curved joint (zg) between intermediate member(Z) and housing (G) is formed via a revolvable rotating body attached onthe intermediate member (Z) and via a cam (Kgz2) in the housing (G). 18.Device in accordance with claim 2, characterized in that the curvedjoint (zw) between intermediate member (Z) and shaft (W) is formed via arevolvable rotating body attached on the intermediate member (Z) and viaa cam (Kwz1) on the shaft (W).
 19. Device in accordance with claim 3,characterized in that the curved joint (zw) between intermediate member(Z) and shaft (W) is formed via a revolvable rotating body attached onthe intermediate member (Z) and via a cam (Kwz1) on the shaft (W). 20.Device in accordance with claim 2, characterized in that the curvedjoint (zw) between intermediate member (Z) and output member (A) isformed via a revolvable rotating body attached on the intermediatemember (Z) and via a cam (Kaz1) on the output member (A).